UPDATE: I have all the reviewers I can handle.
I have about half of the OpenSSH book written. I can start getting feedback on the manuscript. If you’re interested in providing feedback, first read the review process article on my web site.
If you’re still interested after reading that article, send me an email with the subject “OpenSSH review” and tell me that a) you won’t share the review manuscript, and b) why you’d be a good reviewer. I can only manage so many reviewers, so I try to pick readers of every experience level. My email address is m w lucas at black helicopters dot org.
And before you ask: four chapters of the OpenBSD book are finished. Not enough to solicit reviewers. It is proceeding apace, though. I usually work on multiple projects simultaneously, so this is not unusual.